Anti-friction pad



. 95 L. A.,RUNTON 2,872,181

I ANTI-FRICTION PAD Filed Sept 26, 1956 20 K/PAFI'CUED & TEFLON wn? vii/7s a INVENTOR. 4561/5 PUNTU Wm/PD W A 77 ORNE Y ANTI-FRICTION PAD .Leslie A, Runton, Middle Haddarn', Conn assignor to 1 TheRuss ell ManufacturingQCompany, Middletown,

' 1 Conn;, a corporatiorrof Connecticut This invention relates to spring liner pads for separating the leaves of automobile springs and has for an object to provide a pad of the above type having novel and improved characteristics.

Another object is to provide a spring liner pad having improved wearing and lubricating characteristics and which is substantially incompressible under the forces encountered during normal use.

Other objects and advantages will be apparent as the nature of the invention is more fully disclosed.

The pad of the present invention is of the general type shown in the Walters et a1. Patent No. 2,681,223, dated June 15, 1954. This patent shows and describes a pad composed of a plurality of plies of woven cotton fabric with bosses woven integrally into the upper ply. The bosses comprise a plurality of successive rows of loops forming in effect a plurality of parallel fillerwise ribs which together form a rectangular boss or bead projecting above the surface of the fabric, the purpose of which is to position and retain the pad in place during use. The pad is impregnated with a lubricant and binder such as paraffin Wax.

While liner pads of the above type possess many excellent characteristics, it has been found that when the pad is subjected to continued high pressure between the leaves of an automobile spring the pad becomes compressed and may become loose or even slip out of its pocket between the leaves of the spring.

A further object of the present invention is accordingly to provide a pad of the above type which retains its thickness during normal use and which possesses the required lubricating properties to prevent surface damage and reduce wear.

These objects are accomplished in accordance with the present invention by weaving the pad from yarn at least the major portion of which consists of Kraftcord and Teflon (polymerized tetrafluorethylene). Kraftcord is defined as a paper or paperlike strip spirally twisted into the form of a partially collapsed tube. Such Kraftcord yarn is readily available, and is of the type which is commonly used in the carpet industry.

It has been found that Kraftcord, when impregnated with paraifin and compressed as described herein, becomes substantially solid in form and retains its compacted form after the compressing force has been removed. When such a pad is inserted between the spring leaves it does not become further compressed during normal use.

The invention will be better understood by referring to the following description taken in connection with the accompanying drawing in which a specific embodiment thereof has been set forth for purposes of illustration.

In the drawings:

Fig. 1 is a plan view of a web embodying the present invention showing the Kraftcord and Teflon yarns;

Fig. 2 is a side elevation thereof;

Fig.1 3 is a partial sectiontaken on the line 3-3 of :Fig. 1 showing the structure after impregnation and compacting;

Fig.4. is "a perspective view. of a finished. pad cut from the web of Fig. 1;

1 Fig. 5 is an-enlarged-and expanded. sectional view showing the details of the weave;

. Fig. 6 is aQdetail view.- illustrating the. form 'of' the Kraftcord. yarn; and

Fig. 7 is ar brokenidetail' view showingthe liner pad in place betweemthe. leaves of; an automobile spring. Referring. to jthe.:drawinglmore inu-detaiLuthe. invention is shown as embodied in a web 10 which is of the general type disclosed in the Walters et al. patent above mentioned and may comprise an upper ply 11 and a lower ply 12 secured together by binder warp 13, with a plurality of rows of loops 14 woven into the upper ply 11 and forming a rectangular boss 15.

In accordance with this invention the web 10 is woven from Kraftcord yarn 16 and Teflon yarn 17. The Kraft cord yarns 16 are in the form of a partially collapsed twisted tube of paperlike material as illustrated in Fig. 6 and are initially larger in diameter than the Teflon yarns 17. The Kraftcord is extremely flexible. Hence the web can be lightly woven. The Kraftcord yarn 16 and Teflon yarns 17 may be alternated as warps or may be used in different proportions, according to the result to be obtained. Both sets of yarns are exposed on the upper and lower surfaces of the web 10 and on the upper surface of the bosses 15. The filler yarn may be composed of cotton or of Kraftcord.

The web is impregnated with a bonding and lubricating agent and is then cut into square pads .20, as indicated in Pig. 4. The binding agent is capable of forming with the yarn when completed a rigid structure.

Various known types of bonding agent may be used for this purpose, for example, paraffin wax, caranuba wax, metal stearates, natural or synthetic resins or polyester resins.

The bonding agent is retained in and around the Kraftcord yarns 16 but does not adhere to the Teflon yarns 17. Hence the Teflon yarns are exposed at the surfaces of the web while the Kraftcord yarns retain and are embedded in the impregnant.

The web is preferably impregnated before the web is cut to form the individual pads 20 although the pads may be impregnated after cutting if desired. After impregnation the web or pads are die pressed under a high pressure suited to collapse the Kraftcord yarn into a flat calendered form and to compact the bonding agent to for? a hard rigid substantially solid structure as indicated in ig. 3.

Tr" the bonding agent is of the'thermosetting type the die may be heated to cure and set the resin into rigid form.

After compression the Kraftcord remains in calendered form due to its lack of resilience and becomes thinner than the Teflon so that the Teflon becomes exposed on the surface of the web to provide a low friction surface which does not require lubrication during use as an anti-friction pad.

The pads are inserted between the ends of the leaves 21 of a spring with the bosses 15 seated in depressions 22 formed in the leaves 21 to secure the pads in place.

In this construction the compacted pad is substantlally incompressible under normal conditions of use. Hence it does not lose thickness and become loose even after long periods of use. The nature of the impregnant and the characteristics of the Teflon yarn provide a low friction surface which materially reduces the wear and obviates the necessity for lubrication.

Obviously the web or pad may be adapted for various =rPatented- Feb. 3, 1$59 Although a specific embodiment has been shown for purposes of illustration it is to be understood that the invention may be applied to various uses and adaptations as will be apparent to a'person skilled in the art.

What is claimed is:

A spring liner pad forruse between the leaves of a spring, comprising a layer of woven fabric having a raised boss projecting upwardly therefrom to seat in a recess in the spring leaf, said boss being woven integral with said layer, said woven fabric being composed of a spirally twisted paper tube, impregnated with a bonding agent and compacted to collapsed calendered state 4 to form a rigid, compression-resistant structure, and polymerized tetrafluorethylene yarn, said polymerized tetrafluorethylene yarn being thicker than said collapsed tube whereby it is exposed at the surfaces of said pad and forms the anti-friction surface and boss.

References Cited in the file of this patent UNITED STATES PATENTS 2,348,942 Watson May 16, 1944 2,580,436 Knoblaugh Jan. 1, 1952 2,666,637 Lindeman Ian. 19, 1954 2,667,347 Jacobs Ian. 26, 1954 2,681,223 Walters June 15, 1954 2,804,886 White Sept. 3. 1957 

